Protective sheet sticking apparatus

ABSTRACT

A protective sheet sticking apparatus includes a cutting unit that cuts a protective sheet stuck to a wafer along an outer circumference of the wafer while bringing a cutting part of a cutting blade into contact with the outer circumference of the wafer. The cutting unit has a cutting blade support part that supports the cutting blade rotatably in such a manner that the direction of a cutting edge of the cutting part is adjustable from the outside in the radial direction of the wafer to the inside. The cutting blade support part includes a first biasing spring that makes biasing to cause the cutting part to be oriented toward the inside and a second biasing spring that makes biasing to cause the cutting part to be oriented toward the outside in order to prevent the cutting part from being oriented toward the inside by a predetermined angle or larger.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a protective sheet sticking apparatus.

Description of the Related Art

Conventionally, in a semiconductor manufacturing process, a protectivesheet sticking apparatus that sticks a protective sheet such as aprotective tape to a surface of a wafer as an adherend in which pluralsemiconductor devices are formed and cuts the stuck protective sheet bya cutting blade along the outer edge of the wafer is used (for example,refer to Japanese Patent Laid-open No. 2006-005131).

SUMMARY OF THE INVENTION

In such a protective sheet sticking apparatus, the cutting blade movesalong the outer circumferential edge of the wafer and cuts theprotective sheet along the circular wafer. Thereafter, the wafer isthinned by a grinding apparatus or a polishing apparatus or is processedby a laser beam. Normally, the wafer has an orientation flat or notchthat indicates the direction of the crystal orientation at the outercircumference. Even when the protective sheet is cut along the circularshape, if the direction of the cutting edge of the cutting blade is notcaused to be along the orientation flat in particular, the cutprotective sheet widely protrudes from the wafer. Therefore, theprotective sheet becomes an obstacle in the next step and interfereswith grinding or the like. Thus, separately from the method of cuttingthe protective sheet for the circular part, a method in which a table orthe cutting blade is moved along the shape of the orientation flat tocut the protective sheet is executed for the part of the orientationflat. In this case, there is a problem that an actuator for control ofthe table or the cutting blade is required, and therefore the size ofthe apparatus becomes larger, and the cost increases.

Thus, an object of the present invention is to provide a protectivesheet sticking apparatus that can easily cause the direction of acutting part that cuts a protective sheet to follow both a circular partof the outer circumferential edge of a wafer having an orientation flatand the part of the orientation flat.

In accordance with an aspect of the present invention, there is provideda protective sheet sticking apparatus that sticks a protective sheet toa wafer with a circular shape. The protective sheet sticking apparatusincludes a sheet sticking unit that sticks the protective sheet to thewafer held by a table and a cutting unit that cuts the protective sheetstuck to the wafer by the sheet sticking unit along an outercircumference of the wafer while bringing a cutting part of a cuttingblade into contact with the outer circumference of the wafer. Thecutting unit has a cutting blade support part that supports the cuttingblade rotatably in such a manner that a direction of a cutting edge ofthe cutting part is adjustable from an outside in a radial direction ofthe wafer to an inside. The cutting blade support part includes a firstbiasing spring that makes biasing to cause the cutting part to beoriented toward the inside and a second biasing spring that makesbiasing to cause the cutting part to be oriented toward the outside inorder to prevent the cutting part from being oriented toward the insideby a predetermined angle or larger. A direction of the cutting part isadjusted to the predetermined angle with respect to the outercircumference of the wafer.

Preferably, the cutting blade support part further includes a thirdbiasing spring that makes biasing to prevent the direction of thecutting part from being oriented toward the outside by a predeterminedangle or larger.

According to the present invention, it is possible to easily cause thedirection of the cutting part that cuts the protective sheet to followboth the circular part of the outer circumferential edge of the waferhaving the orientation flat and the part of the orientation flat.

The above and other objects, features and advantages of the presentinvention and the manner of realizing them will become more apparent,and the invention itself will best be understood from a study of thefollowing description and appended claims with reference to the attacheddrawings showing a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a configuration example of aprotective sheet sticking apparatus according to an embodiment;

FIG. 2 is a plan view illustrating a wafer that is a sheet stickingtarget of the protective sheet sticking apparatus in FIG. 1;

FIG. 3 is a sectional view illustrating a sheet sticking unit in FIG. 1;

FIG. 4 is a sectional view illustrating the outline of a cutting unit inFIG. 1;

FIG. 5 is a side view illustrating the major part of the cutting unit inFIG. 1;

FIG. 6 is a top view illustrating the outline of the major part of thecutting unit in FIG. 1;

FIG. 7 is a top view illustrating the outline of the major part of thecutting unit in FIG. 1;

FIG. 8 is a top view illustrating the outline of the major part of thecutting unit in FIG. 1; and

FIG. 9 is a plan view illustrating operation of the cutting unit in FIG.1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will be described in detail belowwith reference to the drawings. The present invention is not limited bycontents described in the following embodiment. Furthermore, what can beeasily envisaged by those skilled in the art and what are substantiallythe same are included in constituent elements described below. Moreover,configurations described below can be combined as appropriate. Inaddition, various kinds of omission, replacement, or change of aconfiguration can be carried out without departing from the gist of thepresent invention.

A protective sheet sticking apparatus 1 according to the embodiment ofthe present invention will be described on the basis of the drawings.FIG. 1 is a sectional view illustrating a configuration example of theprotective sheet sticking apparatus 1 according to the embodiment. FIG.2 is a plan view illustrating a wafer 100 that is a sheet stickingtarget of the protective sheet sticking apparatus 1 in FIG. 1. FIG. 3 isa sectional view for explaining a sheet sticking unit 20 in FIG. 1. FIG.4 is a sectional view for explaining the outline of a cutting unit 30 inFIG. 1. FIG. 5 is a side view illustrating the major part of the cuttingunit 30 in FIG. 1. FIG. 6, FIG. 7, and FIG. 8 are all top viewsillustrating the outline of the major part of the cutting unit 30 inFIG. 1. As illustrated in FIG. 1, the protective sheet stickingapparatus 1 includes a table 10, the sheet sticking unit 20, and thecutting unit 30.

The wafer 100 that is a sheet sticking target of the protective sheetsticking apparatus 1 according to the embodiment, i.e. an adherend, is,for example, a circular plate-shaped semiconductor wafer, optical devicewafer, or the like that contains silicon, sapphire, silicon carbide(SiC), gallium arsenide, or the like as the base material. Asillustrated in FIG. 2, in the wafer 100, devices 103 are formed inregions marked out by plural planned dividing lines 102 formed in alattice manner in a front surface 101. In the present embodiment, thewafer 100 has, at the outer circumference, an orientation flat 110 madeby cutting off part of the wafer 100 in a linear manner along thedirection of the crystal orientation in order to indicate the directionof the crystal orientation. Due to this, an outer circumferential edge120 of the wafer 100 has a circular part 121 and a linear part 122 atwhich the orientation flat 110 is formed. The wafer 100 with a circularshape in the present invention includes the wafer 100 having a part madeby cutting off part of the wafer 100 toward the inner circumferentialside relative to the accurately circular shape (orientation flat 110,notch, or the like) at the outer circumference.

A protective sheet 200 stuck to the wafer 100 by the protective sheetsticking apparatus 1 according to the embodiment is, for example, whatis called an adhesive tape having a layer-stacking structure of a baselayer made of a resin and a glue layer formed of an adhesive agent madeof a resin. In the present embodiment, the protective sheet 200 is stuckwith the glue layer side having adhesiveness oriented toward the side ofthe front surface 101 of the wafer 100 and thereby protects the side ofthe front surface 101 of the wafer 100. The protective sheet 200 is notlimited thereto in the present invention and may be stuck to the side ofa back surface 104 on the opposite side to the front surface 101 insteadof the side of the front surface 101 of the wafer 100. A protectivesheet with only a base layer that does not have a glue layer may bepressure-bonded to the wafer 100 while the protective sheet is heated.Furthermore, the protective sheet 200 is not limited to what is calledthe adhesive tape in the present invention and may be what is called athermoplastic resin sheet that is formed into a sheet shape throughpressing and spreading a thermoplastic resin while heating thethermoplastic resin to soften or melt it and obtains adhesiveness byheating.

In the present embodiment, the table 10 is, for example, what is calleda chuck table having a circular disc-shaped frame body in which arecessed part is formed and a suction adhesion part that is fitted intothe recessed part and has a circular disc shape. The suction adhesionpart of the table 10 is formed of porous ceramic and is connected to avacuum suction source that is not illustrated in the diagram through avacuum suction path that is not illustrated in the diagram. The uppersurface of the suction adhesion part of the table 10 is a holdingsurface 11 on which the wafer 100 is placed and that sucks and holds theplaced wafer 100. In the present embodiment, the wafer 100 is placed onthe holding surface 11 with the front surface 101 oriented upward, andthe holding surface 11 sucks and holds the placed wafer 100 from theside of the back surface 104. The holding surface 11 and the uppersurface of the frame body of the table 10 are disposed on the same planeand are formed in parallel to the horizontal plane. In the table 10, acircular annular groove 12 having a diameter similar to the diameter ofthe outer circumference of the wafer 100 is formed in the upper surfaceof the frame body. The groove 12 functions as a clearance groove of acutting blade 31 of the cutting unit 30 to be described later. The table10 is not limited to what is called a porous chuck table in the presentinvention and may be a form that does not have the suction holdingfunction. Furthermore, a chuck table with a smaller diameter than thewafer 100 may be used.

In the present embodiment, the sheet sticking unit 20 has a roller 21that moves in association with rotation while rotating around the axialcenter parallel to the horizontal direction. As illustrated in FIG. 3,the sheet sticking unit 20 rotationally moves the roller 21 from one endof the side of the front surface 101 of the wafer 100 toward the otherend with the interposition of the protective sheet 200. Thereby, whileplacing the protective sheet 200 sequentially from the one end of theside of the front surface 101 of the wafer 100, the sheet sticking unit20 presses the placed protective sheet 200 against the wafer 100 with apredetermined pressing force by the roller 21, to stick the protectivesheet 200 to the front surface 101 of the wafer 100. When the protectivesheet 200 stuck to the wafer 100 is a thermoplastic resin sheet, thesheet sticking unit 20 heats the protective sheet 200 from the side ofthe roller 21 or the side of the table 10 to soften it in addition tothe rotational movement of the roller 21 and thereby sticks the softenedprotective sheet 200 to the front surface 101 of the wafer 100.

The sheet sticking unit 20 is not limited to the form including theroller 21 in the present invention, and the protective sheet 200 may bepressed against and stuck to the front surface 101 of the wafer 100 by apressing plate having a pressing surface with a shape and area similarto those of the table 10. Furthermore, the sheet sticking unit 20 maystick the protective sheet 200 to the front surface 101 of the wafer 100by blowing wind thereto. Moreover, with what is called a vacuum mounter,the protective sheet 200 may be stuck to the wafer 100 by using an airpressure difference.

As illustrated in FIG. 4, the cutting unit 30 has the cutting blade 31,a circular plate 32 that holds the cutting blade 31 toward the outercircumferential edge 120 of the wafer 100, a cutting blade support part33 that supports the cutting blade 31 rotatably around the axial centerparallel to the vertical direction (Z-axis direction in FIG. 4) in sucha manner that the direction of a cutting edge 312 of a cutting part 311of the cutting blade 31 is adjustable, and a rotational drive sourcethat rotationally drives the circular plate 32 around the axial centerparallel to the vertical direction and is not illustrated in thediagram. As illustrated in FIG. 4, the cutting blade support part 33 isdisposed on the lower side of the outer circumferential part of thecircular plate 32 and rotationally moves along the circumferentialdirection of the circular plate 32 by rotating the circular plate 32around the axial center by the rotational drive source. The cuttingblade 31 rotationally moves along the circumferential direction of thecircular plate 32 in association with this rotational movement of thecutting blade support part 33. As illustrated in FIG. 4, the cuttingunit 30 rotates the circular plate 32 around the axial center by therotational drive source in a state in which the cutting edge 312 of thecutting part 311 of the cutting blade 31 is made to cut into theprotective sheet 200 and is slightly separated upward from the groove12. Thereby, the cutting unit 30 rotationally moves the cutting blade 31along the outer circumferential edge 120 of the wafer 100 and cuts off aprotruding part 201 that protrudes from the outer circumferential edge120 of the wafer 100 in the radial direction in the protective sheet200.

For the cutting part 311 of the cutting blade 31, as illustrated in FIG.5, a cutting blade heating part 313 that heats the cutting part 311 ofthe cutting blade 31 is disposed. The cutting unit 30 heats and softensthe protective sheet 200 through the cutting part 311 of the cuttingblade 31 and facilitates the cutting by heating the cutting part 311 ofthe cutting blade 31 by the cutting blade heating part 313. Therefore,without generating a burr in the protective sheet 200, the protectivesheet 200 can be cut by the cutting part 311 of the cutting blade 31 inconformity with the shape of the outer circumferential edge 120 of thewafer 100 more accurately.

As illustrated in FIG. 5, the cutting blade support part 33 includes arotating shaft member 34, a support part main body 35, a cylinder 36, afirst biasing spring 37, a damper 38 including a second biasing spring381, and a damper 39 including a third biasing spring 391. The rotatingshaft member 34 is disposed on the lower side of the outercircumferential part of the circular plate 32 in parallel to thevertical direction (Z-axis direction in FIG. 5) and is supportedrotatably around the axial center parallel to the vertical directionrelative to the circular plate 32.

The support part main body 35 is disposed to be fixed to the lower sideof the rotating shaft member 34 in such a manner as to rotate around theaxial center of the rotating shaft member 34 integrally with therotating shaft member 34. The support part main body 35 supports thecutting blade 31 on the lower side. The support part main body 35supports the cutting blade 31 in such a manner as to orient thedirection of the cutting edge 312 of the cutting part 311 of the cuttingblade 31 in the circumferential direction of the circular plate 32substantially. As illustrated in FIG. 6, the support part main body 35has a shape that extends along the circumferential direction of thecircular plate 32 substantially. The support part main body 35 rotatesaround the axial center together with the rotating shaft member 34through application of an external force to any of regions on a tip sidethat is the side of the cutting edge 312 of the cutting part 311relative to the rotating shaft member 34 and a base end side on theopposite side to the tip side in an outer surface 351 and an innersurface 352 oriented toward the outside and the inside, respectively, inthe radial direction of the circular plate 32. The direction of thecutting edge 312 of the cutting part 311 is oriented inward in theradial direction or outward in the radial direction relative to thecircumferential direction of the circular plate 32 through rotation ofthe support part main body 35 around the axial center together with therotating shaft member 34.

The cylinder 36 is disposed on the lower side of the outercircumferential part of the circular plate 32 with theextension-retraction direction oriented in the radial direction of thecircular plate 32. The cylinder 36 is controlled by a control unit thatis included in the protective sheet sticking apparatus 1 and is notillustrated in the diagram and is switched between two stages of anextended state and a retracted state simply. One end part of thecylinder 36 is fixed to the lower side of the outer circumferential partof the circular plate 32 and a plate component 361 is disposed to beconnected to the other end part that moves along the radial direction ofthe circular plate 32 in response to extension and retraction.

The first biasing spring 37 is disposed with the extension-compressiondirection oriented in the radial direction of the circular plate 32. Asillustrated in FIG. 5 and FIG. 6, one end of the first biasing spring 37is connected to the region on the base end side in the outer surface 351of the support part main body 35, and the other end is connected to theplate component 361. When the cylinder 36 is in the retracted state, asillustrated in FIG. 6, the first biasing spring 37 becomes the state ofbeing neither extended nor compressed and does not apply an externalforce to the support part main body 35. Thus, when the cylinder 36 is inthe retracted state, the angle of the inclination of the direction ofthe cutting edge 312 of the cutting part 311 toward the inside in theradial direction with respect to the circumferential direction of thecircular plate 32 (cutting edge inclination angle) becomes θ1=0 degreesas illustrated in FIG. 6. Regarding the cutting edge inclination angle,in the present embodiment, the angle when the direction of the cuttingedge 312 of the cutting part 311 is oriented in the circumferentialdirection of the circular plate 32 is defined as 0 degrees as the basis,and a positive value is employed as the value of the angle when thedirection of the cutting edge 312 of the cutting part 311 is orientedinward in the radial direction relative to the circumferential directionof the circular plate 32.

When the plate component 361 moves outward in the radial direction inassociation with switching of the cylinder 36 to the extended state, asillustrated in FIG. 7 and FIG. 8, the first biasing spring 37 isextended in association with the movement of the plate component 361 andapplies an external force directed outward in the radial direction tothe base end side of the outer surface 351 of the support part main body35. Thereby, the first biasing spring 37 rotates the support part mainbody 35 together with the rotating shaft member 34 around the axialcenter in a clockwise manner as viewed from the upper side and rotatesthe direction of the cutting edge 312 of the cutting part 311 toward theinside in the radial direction relative to the circumferential directionof the circular plate 32. Due to this, when the cylinder 36 becomes theextended state, the cutting edge inclination angle becomes an anglelarger than 0 degrees, and becomes θ2 (>0 degrees) in the exampleillustrated in FIG. 7 and becomes θ3 (>0 degrees) in the exampleillustrated in FIG. 8. As above, when the cylinder 36 is in the extendedstate, the first biasing spring 37 biases the direction of the cuttingedge 312 of the cutting part 311 to orient the direction inward in theradial direction relative to the circumferential direction of thecircular plate 32.

The damper 38 internally including the second biasing spring 381 isdisposed with the extension-compression direction oriented in the radialdirection of the circular plate 32. In the damper 38 internallyincluding the second biasing spring 381, as illustrated in FIG. 5 andFIG. 6, one end 382 is oriented toward the region on the tip side in theinner surface 352 of the support part main body 35, and the other end isfixed to the lower side of the outer circumferential part of thecircular plate 32 with the interposition of a fixing component 383. Inthe damper 38 internally including the second biasing spring 381, whenthe direction of the cutting edge 312 of the cutting part 311 isoriented inward in the radial direction by a predetermined angle (forexample, θ3 illustrated in FIG. 8) or larger relative to thecircumferential direction of the circular plate 32 due to biasing by thefirst biasing spring 37, the one end 382 gets contact with the region onthe tip side in the inner surface 352 of the support part main body 35and applies an external force thereto to prevent the direction of thecutting edge 312 of the cutting part 311 from being oriented inward inthe radial direction by the predetermined angle or larger relative tothe circumferential direction of the circular plate 32. As above, thesecond biasing spring 381 makes the biasing to cause the cutting edge312 of the cutting part 311 to be oriented outward in the radialdirection in order to prevent the direction of the cutting edge 312 ofthe cutting part 311 from being oriented inward in the radial directionby the predetermined angle or larger relative to the circumferentialdirection of the circular plate 32.

The damper 39 internally including the third biasing spring 391 isdisposed with the extension-compression direction oriented in the radialdirection of the circular plate 32. In the damper 39 internallyincluding the third biasing spring 391, as illustrated in FIG. 5 andFIG. 6, one end 392 is oriented toward the region on the tip side in theouter surface 351 of the support part main body 35 and the other end isfixed to the lower side of the outer circumferential part of thecircular plate 32 with the interposition of a fixing component 393. Inthe damper 39 internally including the third biasing spring 391, whenthe direction of the cutting edge 312 of the cutting part 311 isoriented outward in the radial direction by a predetermined angle (forexample, θ1=0 degrees illustrated in FIG. 6) or larger relative to thecircumferential direction of the circular plate 32 due to a reactionforce (normal force) from the outer circumferential edge 120 of thewafer 100, and so forth, the one end 392 gets contact with the region onthe tip side in the outer surface 351 of the support part main body 35and applies an external force thereto to prevent the direction of thecutting edge 312 of the cutting part 311 from being oriented outward inthe radial direction by the predetermined angle or larger relative tothe circumferential direction of the circular plate 32. As above, thethird biasing spring 391 makes the biasing to cause the cutting edge 312of the cutting part 311 to be oriented inward in the radial direction inorder to prevent the direction of the cutting edge 312 of the cuttingpart 311 from being oriented outward in the radial direction by thepredetermined angle or larger relative to the circumferential directionof the circular plate 32.

As above, the cutting unit 30 orients the direction of the cutting edge312 of the cutting part 311 inward in the radial direction relative tothe circumferential direction of the circular plate 32 by the firstbiasing spring 37, and makes restriction, by the second biasing spring381 and the third biasing spring 391, to prevent the direction of thecutting edge 312 of the cutting part 311 from inclining inward in theradial direction and outside in the radial direction, respectively, bythe predetermined angle or larger.

The control unit that is included in the protective sheet stickingapparatus 1 and is not illustrated in the diagram controls operation ofvarious kinds of constituent elements of the protective sheet stickingapparatus 1 and causes the protective sheet sticking apparatus 1 toexecute sticking processing to stick the protective sheet 200 to thefront surface 101 of the wafer 100 and cutting-off processing to cut offthe protruding part 201 of the protective sheet 200. The control unit ofthe protective sheet sticking apparatus 1 includes a computer system inthe present embodiment. The computer system included in the control unithas a calculation processing device having a microprocessor like acentral processing unit (CPU), a storing device having a memory like aread only memory (ROM) or random access memory (RAM), and aninput-output interface device. The calculation processing device of thecontrol unit executes calculation processing in accordance with acomputer program stored in the storing device of the control unit andoutputs a control signal for controlling the protective sheet stickingapparatus 1 to the respective constituent elements of the protectivesheet sticking apparatus 1 through the input-output interface device ofthe control unit.

Next, the present specification will describe operation of the cuttingunit 30 of the protective sheet sticking apparatus 1 according to theembodiment by using drawings. FIG. 9 is a plan view illustrating theoperation of the cutting unit 30 in FIG. 1. As illustrated in FIG. 9,the cutting unit 30 cuts the protective sheet 200 stuck to the wafer 100by the sheet sticking unit 20 along the outer circumferential edge 120of the wafer 100 while bringing the cutting part 311 of the cuttingblade 31 into contact with the outer circumferential edge 120 of thewafer 100, to cut off the protruding part 201. In the presentembodiment, the cutting unit 30 cuts the protective sheet 200 by thecutting part 311 of the cutting blade 31 from the side of the protectivesheet 200 stuck to the wafer 100. However, the configuration is notlimited thereto in the present invention, and the protective sheet 200may be cut from the side of the wafer 100.

First, the cutting unit 30 makes the cutting edge 312 of the cuttingpart 311 of the cutting blade 31 cut into the protective sheet 200 andpositions the cutting edge 312 into the state of being slightlyseparated upward from the groove 12. Then, the cutting unit 30 switchesthe cylinder 36 from the retracted state to the extended state andbiases the direction of the cutting edge 312 of the cutting part 311 tocause the direction to be oriented inward in the radial directionrelative to the circumferential direction of the circular plate 32 bythe first biasing spring 37. Thereby, the cutting unit 30 brings thecutting part 311 into contact with the outer circumferential edge 120 ofthe wafer 100. Next, by rotating the circular plate 32 around the axialcenter by the rotational drive source, the cutting unit 30 moves thecutting part 311 of the cutting blade 31 along the outer circumferentialedge 120 of the wafer 100 while bringing the cutting part 311 intocontact with the outer circumferential edge 120 of the wafer 100.Thereby, the cutting unit 30 cuts the protective sheet 200 stuck to thewafer 100 along the outer circumferential edge 120 of the wafer 100.

When the cutting part 311 of the cutting blade 31 is moving along theouter circumferential edge 120 of the wafer 100 while being contact withthe outer circumferential edge 120, while the cutting part 311 receivesthe biasing by the first biasing spring 37 and the direction of thecutting edge 312 is oriented inward in the radial direction relative tothe circumferential direction of the circular plate 32, the cutting part311 receives a reaction force from the outer circumferential edge 120 inassociation with being pressed against the outer circumferential edge120 of the wafer 100, and the direction of the cutting edge 312 ispushed back outward in the radial direction relative to thecircumferential direction of the circular plate 32. Due to this, whenthe cutting part 311 of the cutting blade 31 is moving along thecircular part 121 of the outer circumferential edge 120 of the wafer 100while being contact with the circular part 121, the cutting edgeinclination angle is kept at an angle suitable for the cutting of theprotective sheet 200 (for example, approximately θ2) as illustrated inFIG. 7.

Because the orientation flat 110 is formed by cutting off part of thewafer 100 toward the inside relative to the circumference, the reactionforce received by the cutting part 311 of the cutting blade 31 from thelinear part 122 at which the orientation flat 110 is formed is weakerthan the reaction force received from the circular part 121. Thus, whenthe cutting part 311 of the cutting blade 31 is moving along the linearpart 122 at which the orientation flat 110 is formed in the outercircumferential edge 120 of the wafer 100 while being contact with thelinear part 122, the cutting edge inclination angle becomes a largerangle (for example, approximately θ3) than that when the cutting part311 is moving along the circular part 121 as illustrated in FIG. 8. Whenmoving along the linear part 122, the cutting part 311 of the cuttingblade 31 can smoothly move in such a manner as to follow the linear part122 at which the orientation flat 110 is formed in the outercircumferential edge 120 of the wafer 100 because the cutting edgeinclination angle is larger than that when the cutting part 311 ismoving along the circular part 121. As above, for the cutting part 311of the cutting blade 31, without particularly controlling the biasingforce by the first biasing spring 37, the cutting edge inclination angleis automatically adjusted according to the shape of the outercircumferential edge 120 of the wafer 100, and the movement path isadjusted to follow the outer circumferential edge 120 of the wafer 100.

Furthermore, the cutting part 311 of the cutting blade 31 is restrictedby the damper 38 internally including the second biasing spring 381 insuch a manner that the direction of the cutting edge 312 of the cuttingpart 311 is prevented from inclining inward in the radial direction bythe predetermined angle or larger. Therefore, even when the cutting part311 is moving along the linear part 122 at which the orientation flat110 is formed, the direction of the cutting edge 312 is prevented frombeing oriented inward in the radial direction beyond the range of thecutting edge inclination angle in which the protective sheet 200 can becut sufficiently smoothly. Moreover, the cutting part 311 of the cuttingblade 31 is restricted by the damper 39 internally including the thirdbiasing spring 391 in such a manner that the direction of the cuttingedge 312 of the cutting part 311 is prevented from inclining outward inthe radial direction by the predetermined angle or larger. Therefore,the direction of the cutting edge 312 is prevented from being orientedoutward in the radial direction beyond the range of the cutting edgeinclination angle in which the protective sheet 200 can be cutsufficiently smoothly.

The protective sheet sticking apparatus 1 according to the embodimenthaving the above configuration makes biasing, by the first biasingspring 37, to cause the direction of the cutting edge 312 of the cuttingpart 311 to be oriented inward in the radial direction relative to thecircumferential direction of the circular plate 32. Therefore, theprotective sheet sticking apparatus 1 can easily cause the direction ofthe cutting edge 312 of the cutting part 311 to follow both the circularpart 121 of the outer circumferential edge 120 of the wafer 100 havingthe orientation flat 110 and the linear part 122 of the orientation flat110. Thus, the protective sheet sticking apparatus 1 according to theembodiment provides an effect that the protective sheet 200 can beproperly cut also for the wafer 100 having the orientation flat 110without newly adding an actuator for controlling the table or thecutting blade.

Furthermore, the protective sheet sticking apparatus 1 according to theembodiment makes biasing outward in the radial direction, by the secondbiasing spring 381, to prevent the direction of the cutting edge 312 ofthe cutting part 311 from being oriented inward in the radial directionby the predetermined angle or larger relative to the circumferentialdirection of the circular plate 32. Therefore, the protective sheetsticking apparatus 1 can prevent the direction of the cutting edge 312of the cutting part 311 from excessively inclining inward in the radialdirection. This provides an effect that the protective sheet 200 can becut more properly also for the linear part 122 at which the orientationflat 110 is formed.

Moreover, the protective sheet sticking apparatus 1 according to theembodiment makes biasing inward in the radial direction, by the thirdbiasing spring 391, to prevent the direction of the cutting edge 312 ofthe cutting part 311 from being oriented outward in the radial directionby the predetermined angle or larger relative to the circumferentialdirection of the circular plate 32. Therefore, the protective sheetsticking apparatus 1 can prevent the direction of the cutting edge 312of the cutting part 311 from excessively inclining outward in the radialdirection. This provides an effect that the protective sheet 200 can becut more properly also for the wafer 100 having the orientation flat110.

It is noted that the present invention is not limited to theabove-described embodiment. That is, the present invention can becarried out with various modifications without departing from the gistof the present invention. For example, in the above-describedembodiment, the protective sheet 200 is cut along the outercircumferential edge 120 of the wafer 100 in which the orientation flat110 is formed. However, in the present invention, the protective sheet200 may be cut along the outer circumferential edge 120 of the wafer 100in which not only the orientation flat 110 but a part made by cuttingoff part of the wafer 100 into a given shape toward the innercircumferential side relative to the accurately circular shape is formedat the outer circumference.

The present invention is not limited to the details of the abovedescribed preferred embodiment. The scope of the invention is defined bythe appended claims and all changes and modifications as fall within theequivalence of the scope of the claims are therefore to be embraced bythe invention.

What is claimed is:
 1. A protective sheet sticking apparatus that sticksa protective sheet to a wafer with a circular shape, the protectivesheet sticking apparatus comprising: a sheet sticking unit that sticksthe protective sheet to the wafer held by a table; and a cutting unitthat cuts the protective sheet stuck to the wafer by the sheet stickingunit along an outer circumference of the wafer while bringing a cuttingpart of a cutting blade into contact with the outer circumference of thewafer, wherein the cutting unit has a cutting blade support part thatsupports the cutting blade rotatably in such a manner that a directionof a cutting edge of the cutting part is adjustable from an outside in aradial direction of the wafer to an inside, the cutting blade supportpart includes a first biasing spring that makes biasing to cause thecutting part to be oriented toward the inside, and a second biasingspring that makes biasing to cause the cutting part to be orientedtoward the outside in order to prevent the cutting part from beingoriented toward the inside by a predetermined angle or larger, and adirection of the cutting part is adjusted to the predetermined anglewith respect to the outer circumference of the wafer.
 2. The protectivesheet sticking apparatus according to claim 1, wherein the cutting bladesupport part further includes a third biasing spring that makes biasingto prevent the direction of the cutting part from being oriented towardthe outside by a predetermined angle or larger.